Method of making anhydrous magnesium chloride



Patented Sept. 6, 1932 UNITED STATES PA ENT-orator:

Kenn STAIB, on BITTERFELD, GERMANY, AssrGnon, BY nsnn AssIGn Enrsf'ro MAGNESIUM DEVELOPMENT CORPORATION, A CORPORATION on DELAWARE METHOD OF MAKING ANHYDROUS MAGNESIUM CHLORIDE No Drawing. Application filed March 2, 1927, Serial No. 172,216, and. in Germany March 6, 1926,

This invention relates to the production of molten anhydrous magnesium chloride from magnesium oxide. In maintaining reactions between solids and gases, especially '6 at elevated temperatures, it is often diificult to provide the solid substance with a surface sufiiciently large to maintain the reaction at the desired velocity, without provoking, where the reaction is exothermic, a detrimental sintering or melting. Consequently it is necessary to either continuously ex pose fresh surfaces to the reactant gas by agitating or stirring the pulverized solid substances or to mix the finely pulverized solid substances with pore-forming materials and to then convert the mixture into solid form.

It has been attempted to avoid these difliculties by applying the principles of coaldust firing to the exothermic oxidation of substances which are easily oxidized by air,

for instance, sulfides, or to the nitrogenization of carbides. A similar process has also been recommended for the production of metal halides, particularly aluminum chloride in volatile form, from raw material containing the corresponding metal oxide, by injecting such pulverized raw material, together with fuel, a combustion-supporting gas such as air, and a halogen, into a combustion and reaction chamber. However, the presence of air in the reaction mixture causes partial decomposition of the halide formed and thus, although rendering the process thermally self-supporting, tends to diminish the amount of product obtained.

Another process of making volatile aluminum chloride provides for the introduction of aluminous material, fuel (carbon) and chlorine without a combustion-supporting gas into a combustion and reaction chamber. In this case, however, it is necessary to apply external heat throughout the entire course of reaction. 7

The present invention is concerned with the production of molten anhydrous magnesium chloride from magnesium oxide or magnesium oxide-bearing materials, and it has as a principal object the avoidance of the difilculties of such former processes, that 50 is to say, the avoidance of the necessity of introducing, with the reaction mixture prop er, a combustion-supporting gas and the necessity of external heating during the reaction. 7 I

According to the present invention the. magnesium oxide or the magnesium oxide-- bearing material is suspended in a current of gas consisting of chlorine and carbon monoxlde and 1s 1n ected thus into a ,reaction chamber which has been sufficiently preheat.

ed to initiate the reaction; For this latter purpose the reaction chamber is preferably preheated to the reaction temperature by any; convenient heating device. This initial preheating once accomplished, additional heat ing maybe dispensed with, the heat of reaction sufficing to maintain a proper reaction temperature. In order that the invention may be fully understood the following examples will be referred to.

E wamples 1. Finely ground magnesium oxide is, by

means of a. gas current consisting of equal parts, by volume, of chlorine and carbon monoxide, injected through a nozzle into a chamber preheated to 700 C. The temperature of the reaction chamber is maintained by the reaction heat which amounts to 76 calories per one gram-molecule of MgCl The little drops of the resulting anhydrous magnesium chloride collect so that the molten mass can be withdrawn from the bottom of the reaction chamber.

2. Instead of blowing in magnesium oxide by means of carbon monoxide and chlorine as described in Example 1, chlorine alone may also be used as an injecting medium and made to react with a finely ground mixture of magnesium oxide and a suitable carbonaceous material, such as coal-dust.

The ratio of components may be, as a rule, between one and two atoms of carbon to two molecules of magnesium oxide. As the reminimum excess of coal is left in the molten final product. However, an undesired excess of coal may. also ultimately be removed from the melt.

I claim 1. The process which comprises introducing finely subdivided magnesium oxide suspended in a current consisting of chlorine and carbon monoxide, into a reaction chamber ,sufliclently preheated to start the reaction,

and Withdrawing molten chloride from said chamber, the heat of reaction suflicing to maintain the reaction. a

2. The process Which comprises introducing finely subdivided magnesium oxide sus-' pended 1n a current consisting of approximately equal parts, by volume, of chlorlne and carbon monoxide into a reaction chamber sufficiently preheated to start the reaction and Withdrawing molten chloride from said chamber, the heat of reaction sufficing to maintain the reaction. Y

3. The process which comprises injecting the finely subdivided magnesium oxide suspended in a current consisting of approximately equal parts, by volume, of chlorine and carbon monoxide into a reaction chamber preheated to a temperature of about 700 C., allowing the resulting drops of anhydrous magnesium chloride to gather, and WithdraW- ing the molten mass from said chamber, the

heat of reaction sufficing to maintain the reaction.

In testimony whereof I aflix my signature.

KARL STAIB. 

